Classifications

• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B5/00—Automatic winding up
  • G04B5/24—Protecting means preventing overwinding

Definitions

• the present invention relates to a motor spring for mounting in a self-winding watch engine cylinder to minimize wear of the barrel drum in which it is mounted.
• the automatic winding of a watch is done permanently.
• the barrel spring When the barrel spring is fully armed, it must limit its overvoltage to avoid breakage. The movements of the oscillating mass must have no effect on the spring when it has reached its maximum tension.
• the barrel spring of the automatic watch typically has a sliding flange that functions as a valve. Indeed, when the armature has reached its maximum value, the spring will slide a certain angle in the barrel drum.
• the wall may comprise notches whose role is to limit the sliding of the flange during overvoltages of the mainspring. In this case, the end of the mainspring usually stops in each notch.
• the smooth operation of the sliding flange is delicate and depends on several factors such as the shape and the tension of the flange, the material and the quality of the machining of the barrel drum, the galvanic treatment, the lubrication of the barrel and its jurisdiction. It has been observed that, during the sliding of the flange during overvoltages of the mainspring, the end of the motor spring comes to bear against the inner wall of the barrel drum. This tends to produce premature wear of the wall, by chiseling.
• An object of the present invention is to provide a barrel drive spring free from the limitations of known springs.
• Another object of the invention is to provide a barrel drive spring adapted to come into contact with the inner wall of the barrel drum in at least one tangent plane.
• a motor spring comprising: a first spiral-shaped spring portion having a first curvature and having an inner end intended to be fixed to a shaft of a barrel; a second spring portion extending from the first spring portion and arranged to cooperate with a barrel of a barrel, the second spring portion having a second curvature of opposite direction to the first curvature and a descending radius of curvature of the end close to the first spring portion at an outer end of the second spring portion; the second spring portion further comprising a tangency zone having a radius of curvature smaller than the radius of curvature of the drum of a cylinder in which the mainspring is intended to be mounted, so that when the mainspring is mounted in the barrel, the tangent zone comes into contact with the inner surface of the drum in at least one line of intersection between the tangent zone and the
• An advantage of the present solution is that the motor spring 1 comes into contact with the inner wall of the barrel drum in at least one tangent plane.
• the chipping effect observed in the case of springs conventional motor is replaced by sliding of the contact region. The wear of the drum is therefore considerably reduced.
• FIG. 1 to 1 c illustrate a motor spring 1 intended to be mounted in a timepiece motor cylinder in its free state, according to one embodiment
• Figure 2 shows the motor spring 1 mounted in a motor cylinder, according to one embodiment
• FIG. 3 illustrates a sectional view of a second spring portion of the mainspring comprising a tangency zone, according to one embodiment
• Figure 4 illustrates the zone of tangency, according to another embodiment
• FIG. 5 illustrates the zone of tangency, again according to another embodiment.
• FIG. 1 Figures 1 to 1 c illustrate a motor spring 1 to be mounted in a watch engine cylinder in its free state, that is to say before mounting in the barrel.
• the motor spring 1 mounted in a motor cylinder 30 is shown in FIG. 2.
• the motor spring 1 comprises a first portion 2 of spiral shape having a first curvature and comprising an inner end 3 intended to be fixed on a shaft of the barrel 32, and a second portion 4 extending from the first spring portion and arranged to cooperate with the inner surface of a drum 31 of the barrel 30.
• the second spring portion 4 has a second curvature of opposite direction to the first curvature and a decreasing radius of curvature of end near the first portion spring 2 at an outer end 7 (or spring tip) of the second spring portion 4.
• the first curvature of the first portion 2 of the motor spring 1 has a growing radius.
• the radius of curvature tends towards infinity between the first and second portions 2, 4 (indicated by the number 23 in FIG. 1), then the radius is reversed (curvature of opposite direction) and finally decreases in the second portion 4 to give the motor spring 1 an inverted spiral winding in the form of a letter S or in the form of a ground key.
• the second spring portion 4 comprises a tangency zone 5 having a curvature of opposite direction than the second curvature and a radius of curvature smaller than the barrel drum radius 30.
• the tangent zone 5 comes into contact with the inner surface of the drum 31 in at least one tangent plane, that is to say, along at least one intersection line between the tangent zone 5 and the inner surface of the drum 31.
• the tangency zone 5 has a flexural strength less than that of at least part of the rest of the second spring portion 4.
• a flexural strength can be obtained, for example, in the case where the thickness 9 (or the height) of the mainspring 1 in the zone of tangency 5 is less than the thickness of the motor spring 1 in the second spring portion 4.
• FIG. 3 shows a sectional view in the direction of the thickness of the second spring portion 4.
• the tangency zone 5 further comprises a rectangular slot 8 cut in the material of the motor spring 1.
• the rectangular slot 8 extends over a portion of the outer portion 6 so to further reduce the section, and thus the flexural strength, of the area of tangency with respect to the section and the flexural strength that prevails in the rest of the second spring portion 4.
• rectangular 8 extends to the outer end 7 of the second spring portion 4 so that the outer portion 6 of the motor spring 1 is divided into two parallel blades.
• each of the portions 5 'of the tangent zone 5 results in a point of contact between the tangency zone 5 and the surface Inside the drum 31.
• the position of the tangent zone 5 along the outer portion 6 of the motor spring 1 depends on the position of the slot 8 along the outer portion 6 and its configuration.
• the motor spring 1 is made of a metallic material and a heat treatment is carried out locally in the tangency zone 5.
• the heat treatment is arranged to reduce the bending strength in the zone of tangency 5.
• the tangency zone 5 has been plastically deformed so as to orient the tip of the spring 7 towards the center of the barrel 30, so as to reduce or eliminate, the chipping effect of the tip 7 on the drum 31.
• a bent portion 10 of the second spring portion 4 i.e., a portion of the second spring portion 4 extending from the tangent zone 5 to the outer end 7 has a curvature opposite to that of the second portion of spring 4 and is not in contact with the wall of the drum 31 when the spring 1 is mounted in the barrel 30.
• the area of tangency 5 having a radius of curvature smaller than the radius of curvature of the drum 31 can be likened to a folding zone of the outer portion 6 of the spring 1.
• the curvature in the zone of tangency 5 results in a contact zone 51 with the inner surface of the drum 31 in at least one plane tangential to the zone of tangency 5. Outside the zone of tangency 5, the mainspring 1 may not be in contact with the drum 31.
• FIGS. 1c and 2 it is indeed noted that the outer end 7 of the spring 1 is detached from the drum 31.
• the tangent zone 5 is always in contact with the drum 31 in the contact zone 51, which makes it possible to reduce the forces applied on the tip 7 in the case where the latter is also in contact with the drum 31.
• the tangency zone 5 has undergone plastic deformation so that the bent portion 10 has a curvature in the opposite direction to the second curvature of the second spring portion 4.
• the tip 7 can be in contact with the drum 31 when the spring 1 is mounted in the barrel 30.
• the contact zone 51 will therefore include a contact at the tangency zone 5 and possibly also a contact at the of the tip 7.
• the curvature of the tangency zone 5 is such that the bent portion 10 is flattened and in contact with the inner surface of the drum 31 tangent to the portion bent 10 when the spring 1 is mounted in the barrel 30.
• the outer end 7 is also in tangential contact with the inner surface of the drum 31 and therefore does not produce chipping and / or wear pr matured from the inner surface of the drum 31.
• the contact between the second spring portion 4 and the drum 31 may comprise the tangent zone 5 and one or more other contact zones 51 along the bent portion 10, for example at the outer end 7 or any other point between the tangent zone 5 and the outer end 7.
• the second spring portion 4 may also include a sliding flange 14 shown schematically in Figures 1 and 2 extending along the second spring portion 4. In this case, the sliding flange 14 should not extend. beyond the outer portion 6 and in any case the tangency zone 5.
• the tangent zone 5 extends from where the sliding flange 14 is no longer in contact with the second spring portion 4 (where the non-welded side of the sliding flange stops) and up to the outer end 7.
• the zone of tangency 5 may extend over a portion of the conde portion of spring 4
• the bent portion 10 should not exceed twice the length of the notch, and preferably the length of the notch.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Springs (AREA)

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• 2013
  • 2013-10-04 CH CH01706/13A patent/CH708660A1/fr unknown
• 2014
  • 2014-09-25 EP EP14772389.4A patent/EP3052992A1/de not_active Withdrawn
  • 2014-09-25 WO PCT/EP2014/070548 patent/WO2015049165A1/fr active Application Filing

Non-Patent Citations (1)

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